| 摘要 |
<p>A method for bleaching wood pulp using a hydrogen peroxide solution as a bleaching agent, utilizes a two phase reaction, viz. a short high temperature phase followed by a longer second phase to consume virtually all the hydrogen peroxide remaining after the short phase. The method includes the steps of introducing pulp (10), at a consistency of 10-18 %, to a mixer (100) in which the pulp is heated to a temperature between 80 and 100 °C; adding sufficient sodium hydroxide (15) to bring the pulp to a pH of 9.5-11.5; adding sufficient hydrogen peroxide (35) to provide a peroxide residual after the first reactor column; passing the pulp through a reactor column (400) at a rate providing a reaction time on the column of between 5 to 60 minutes; introducing the pulp to a mixer (500) and reactivating residual hydrogen peroxide by bringing the pulp to a pH of at least 9; and depositing the pulp in a reaction tower (600) and allowing the reaction to proceed for 1-4 hours until a substantial portion of the residual hydrogen peroxide has been consumed.</p> |
